I have a 92 with the same options...I usually leave in in "auto mode" when on the highway in "drive". I believe it allows an overdrive type of gearing for cruising,etc. You can leave it in "auto mode", and leave it in 3 position, around town, and it will ignore the "Overdrive gear". This is probably a more effective use of the powerband for around town. If you choose to utilize the "M, or manual option, it allows you to shift gears manually, and ignores the programmed shift points, but does require you to select the gears, downshift, etc, yourself...hope this helps